1. Field of the Invention
The present invention relates to a slide fastener stringer in which a continuous element row formed of synthetic resin monofilament is woven and fixed on a fastener tape along a side edge of the tape at the same time when the fastener tape is woven.
2. Description of the Related Art
A well known woven slide fastener stringer of this kind is disclosed in, for example, United Kingdom Patent No. 1221114 or Japanese Patent Application Laid-open Publication No. 2-17162. According to the Publication, an element row, which is comprised of plural coil-like coupling element portions arranged in parallel and obtained by forming synthetic resin monofilament, is fixed along a side edge of a fastener tape. The element row is woven and fixed with fixing warp yarns and foundation weft yarns at the same time when the fastener tape is woven.
Each of the coupling element portions is comprised of a coupling head protruded outward from the side edge of the fastener tape, a pair of upper and lower leg portions extended in parallel inward of the tape and a connecting portion for connecting the upper and lower leg portions of adjacent coupling element portions. In the slide fastener stringer disclosed in the aforementioned publication, the foundation weft yarns, each of which is comprised of double yarns, are disposed below the lower leg portion of each coupling element portion. That is, one coupling element portion is woven together with the weft yarn each time when the weft yarn is weft inserted.
In the woven slide fastener stringer disclosed in said United Kingdom Patent, transparent monofilaments are used for warp yarns and weft yarns composing a foundation structure of the fastener tape. Similarly, transparent monofilaments are used for all the warp yarns for fixing the coupling element rows. This woven slide fastener stringer is characterized in that the foundation structure is formed to be coarse and that intersecting portions of the warp yarns and the weft yarns of the foundation structure are made to fused and fixed to each other.
The woven slide fastener stringer disclosed in said Japanese Laid-open Publication No. 2-17162 on the other hand is characterized in its weaving structure. Specifically, as shown in FIG. 11 attached to this specification, each coupling element portion E is supported by 12 fixing warp yarns W1 to W12 in total. On the side of connecting portions of the coupling element portions E, eight warp yarns W5 to W12 are guided in successively in the same repeating patterns of high-high-low-middle in a plan view of the fastener tape. Further, on the side of the coupling heads, four warp yarns W1 to W4 are guided in successively in the repeating patterns of high-middle-low-middle. Here, xe2x80x9chighxe2x80x9d means that the warp yarn supports the upper and lower leg portions L from above, xe2x80x9cmiddlexe2x80x9d means that the warp yarn is disposed between the lower leg portion of the upper and lower leg portions L and the foundation weft yarn w, and xe2x80x9clowxe2x80x9d means that the foundation weft yarn w supports the upper/lower leg portions from below. Meanwhile, in FIG. 11, a representation of the coupling heads of the coupling element portions is omitted to a necessary extent to facilitate understanding graphically.
With such a weaving structure, not only a pitch between adjacent coupling element portions becomes stable, but also density of warp yarns composing a warp yarn pocket can be remarkably intensified without giving any high tension. Thus, the pitches between the coupling element portions are stabilized so that excellent flexibility of the fastener tape can be secured. Consequently, this slide fastener can be sewed to a fabric material, to which the slide fastener is to be attached, such as clothes and bag at high speeds.
The woven slide fastener stringer disclosed in the above-mentioned United Kingdom Patent has a coarse fastener tape, which is composed of transparent monofilaments. Therefore, even when a slide fastener with such a slide fastener stringer is attached to colored clothes for example, it is still possible to perceive the colors of the clothes.
Although, the warp yarns for fixing the coupling element portions are also transparent monofilaments, the slide fastener stringer only has such a weaving structure that four fixing warp yarns run over an upper portion of the coupling element portion and then run below an adjacent coupling element portion, and the respective adjacent fixing warp yarns are woven alternately so as to intersect each other. Therefore, a tightening (fixing) strength of the coupling element portions with respect to a side edge portion of the tape is merely uniform in a region from the connection portions to the coupling heads thereof.
In the slide fastener stringer disclosed in the above-mentioned Japanese Laid-Open Publication, particularly the four warp yarns disposed on the side of the coupling heads, among the fixing warp yarns for fixing the coupling element portions arranged in parallel, run in the same repeating patterns of high-middle-low-middle with respect to the coupling element portions and the weft yarns as described above. The running patterns of the respective adjacent warp yarns are shifted by one pitch of the element portion (weft yarn).
On the other hand, among the fixing warp yarns, eight warp yarns disposed on the side of the connecting portions of the coupling element portions run in the same repeating patterns of high-high-low-middle, which are shifted by one pitch of the element portion (weft yarn).
Both kinds of the repeating patterns of the fixing warp yarns on the sides of the coupling heads and the connecting portions of the paired upper and lower leg portions have no large difference in terms of a weaving structure. Therefore, both the coupling head sides and the connecting portion sides of the paired upper and lower leg portions are fixed with substantially the same strength. Moreover, there is no reference to a variation in said tightening strength of the warp fixing yarns at the coupling head side and the connecting portion side in the above-mentioned Publication. Therefore, the fixing strength of the fixing warp yarns does not vary in a longitudinal direction of the upper and lower leg portions.
Meanwhile, major functions of the coupling element portions in a slide fastener are to guide sliding of a slider during an opening or a closing operation of the fastener by means of the slider, to facilitate introducing of coupling heads smoothly into between adjacent element head portions of opposing coupling element portions when closing the fastener, and to keep a firm coupling between adjacent element head portions when the coupling element portions engage with each other so as not to be disengaged from each other easily.
However, according to a fixing structure for the coupling element portions in the slide fastener stringer as disclosed in the above-mentioned United Kingdom Patent or Japanese Laid-Open Publication, the tightening (fixing) strength of the respective fixing warp yarns for fixing the upper and lower leg portions of the coupling element portions does not vary in the longitudinal direction of the upper and lower leg portions as mentioned above. The fixing strength of the respective coupling element portions to the fastener tape is, however, required to be as large as possible in order to secure a smooth movement of a slider. At the same time, the coupling heads, which are free ends of the coupling element portions, are required to have gaps therebetween sufficient for introducing mating coupling heads and to secure strong couplings between the coupling heads after being coupled with each other.
Furthermore, according to the fixing structure for the element portions in the slide fastener stringer as disclosed in the above-described Japanese Laid-Open Publication, the fixing strength for fixing the paired upper and lower leg portions of each coupling element portion by each fixing warp yarn does not differ in the longitudinal direction of the upper and lower leg portion as described above. Meantime, the fixing strength of each coupling element portion to the fastener tape must be as large as possible in order to ensure a smooth operation of the slider. On the other hand, on the side of the coupling heads, which are free ends of coupling element portions, it is necessary to provide a sufficient gap for introducing a mating coupling head into two adjacent coupling heads to keep a firm coupling between the respective heads after the coupling is attained.
In the slide fastener stringer disclosed in the above-mentioned United Kingdom Patent and Japanese Laid-Open Publication, however, substantially equal tightening forces are applied in the longitudinal direction of the upper and lower leg portions of the coupling element portions, because the fixing structure comprised of such plural fixing warp yarns is substantially the same in the range from the connecting portions to the coupling heads of the coupling element portions. If the weaving tension of the fixing warp yarns is increased more than its normal level in order to increase the tightening force to the fastener tape, not only the tightening force to the fastener tape is increased, but also the tightening force on the side of the coupling heads is increased. As a result, it becomes difficult to couple with a mating slide fastener stringer.
If the weaving tension for each fixing warp yarn is decreased less than its normal level to secure a firm coupling, on the other hand, fixing of the coupling element portions with the fixing warp yarns becomes loose, so that the fixing strength to the entire coupling elements declines. Consequently, the upper and lower leg portions become easy to move in a width direction of the tape, so that not only smooth sliding of the slider is disabled, but also such a defect as a slip-out from the coupling may occur.
According to the present invention, there is provided a woven slide fastener stringer including a fastener tape composed of a plurality of foundation weft yarns and a plurality of warp yarns, and a plurality of coupling element portions, which are continuously formed of synthetic resin monofilament, woven successively along a side edge of the fastener tape with a plurality of element fixing warp yarns arranged in parallel at the same time when the fastener tape is woven, wherein each of the coupling element portions is comprised of a coupling head protruded outward from the side edge of the fastener tape, a pair of upper and lower leg portions extended in parallel inward of the fastener tape from opposite ends of the coupling heads and a connecting portion for connecting each end of the pair of the upper and lower portions with one of a lower leg portion or an upper leg portion of an adjacent coupling element portion. Further, the woven fastener stringer comprises a weaving structure that a tightening force to the pair of the upper and lower leg portions by at least two of the plurality of the element fixing warp yarns arranged in parallel, which are disposed on a side of the coupling heads, is smaller than a tightening force to the pair of the upper and lower leg portions by at least one of the element fixing warp yarns disposed on the side of said connecting portions. The plurality of the element fixing warp yarns are woven into the coupling element portions and foundation weft yarns with said weaving structure.
According to the present invention, a fixing strength on the paired upper and lower leg portions of each coupling element portion to the fastener tape by the fixing warp yarns and a behavior permissible between the coupling heads of the fixed adjacent coupling element portions are made to depend on the weaving structure of the fixing warp yarns. Then, the fixing strength is specified by a relative tightening strength generated based on the weaving structure of the fixing warp yarns with respect to the foundation weft yarn of the fastener tape and the paired upper and lower leg portions of the coupling element portions.
As a result, the fixing of the coupling elements to the fastener tape by the fixing warp yarns is intensified particularly on the side of the connecting portions of the upper and lower leg portion. Thus, the coupling elements are fixed neatly at an equal pitch along the side edge of the fastener tape, so that the opening and closing operation of the fastener by means of a slider can be smoothed. Further, on the side of the coupling heads, a gap between the coupling heads can be expanded or reduced slightly, so that the coupling operation of the respective coupling element portions can be carried out smoothly.
Furthermore, according to the present invention, the difference of the above-described tightening forces is made to depend on structures of the fixing warp yarns. Specifically, it is preferable that said at least one of the plurality of the element fixing warp yarns arranged in parallel, which is disposed on the side of the connecting portions, is composed of a monofilament that is set to have a larger tightening force to the pair of the upper and lower leg portions than a tightening force by any other one of the element fixing warp yarns.
With such a structure, the coupling elements can be more firmly fixed to the fastener tape by the fixing warp yarns, especially at the connecting portion side of the upper and lower leg portions, without any special adjustment of tensions of the respective yarns in a weaving process but only by applying the structures and materials of the yarns. Consequently, the coupling element portions can be fixed along a side edge portion of the fastener tape neatly at an equal pitch, so that the opening and closing operation of the fastener with a slider can be remarkably smoothly carried out, and the respective gaps between the respective adjacent coupling heads can be slightly expanded or reduced, which makes the coupling operation of the respective coupling element portions smooth.
Still further, according to the present invention, the most effective weaving structure of the fixing warp yarns is specified.
That is, according to the present invention, there is provided a woven slide fastener stringer, wherein the at least two element fixing warp yarns disposed on the side of the coupling heads, which have a small tightening force to the paired upper and lower leg portions, intersect two or more of the foundation weft yarns and then run over top faces of adjacent two or more upper leg portions of the upper and lower leg portions at the side of the coupling heads, and repeat the same pattern successively, and the element fixing warp yarns disposed on the side of the connecting portions, which have a large tightening force to the paired upper and lower leg portions, run below one of the foundation weft yarns and then run over a top face of the upper leg portion of the pair of the upper and lower leg portions at the side of the connecting portions, and repeat the same pattern successively.
The weaving structure of the element fixing warp yarns disposed on the side of the connecting portions, which have a large tightening force to the paired upper and lower leg portions, provides the largest tightening force with respect to the upper and the lower leg portions. Therefore, the fixing strength of the coupling element portions to the fastener tape becomes the largest among weaving structures of the coupling elements. On the other hand, according to the weaving structure of the element fixing warp yarns disposed on the side of the coupling heads, which have a smaller tightening force to the paired upper and lower leg portions, a single fixing warp yarn tightens upper portions of two or more pairs of the upper and lower leg portions with respect to the fastener tape. Thus, the two or more upper and lower leg portions tightened in such a manner are allowed to move slightly in a direction of the parallel arrangement of the coupling heads, as compared to the coupling element portions tightened by the element fixing warp yarns disposed on the side of the connecting portions.
Still further, according to the present invention, the patterns of said at least two adjacent element fixing warp yarns disposed on the side of the coupling heads are shifted by one pitch of each of the coupling element portions in a longitudinal direction of the tape. With such a weaving structure, the paired upper and lower leg portions of each of the coupling element portions are tightened by adjacent fixing warp yarns alternately from the right and left. Consequently, not only the slight movement is allowed to a parallel direction of the coupling heads, but also a further stabilized pitch between the coupling heads can be secured.
Still further, according to the present invention, a 1 pick/1 pitch weaving structure is specified. That is, each of the coupling element portions is weft inserted together with the foundation weft yarn, which is weft inserted into each opening. Alternatively, according to the present invention, a two picks/1 pitch weaving structure is specified. Namely, each of the coupling element portions is weft inserted with respect to every other foundation weft yarn which is weft inserted into each opening.
In general, a coarse fastener tape, which has a low weft-yarn density, tends to have a lower fixing strength of fixing warp yarns against coupling element portions, because of its weaving structure. In this case, it is preferable to provide large fineness to the fixing warp yarns on the side of the connecting portions, thereby obtaining a required fixing strength. Therefore, in such a case where a coarse fastener tape is to be obtained, the above-described 1 pick/1 pitch weaving structure is preferable.
Still further, according to the present invention, it is preferable that another foundation warp yarn is disposed between the coupling heads and the element fixing warp yarn disposed at the nearest to the coupling heads, and the foundation warp yarn alternately runs over and below the weft yarns that are weft inserted and arranged adjacent to each other.
Such a weaving structure increases a dimensional stability in the longitudinal direction of the fastener tape along the side edge thereof near the coupling heads. Therefore, coupling between the coupling elements can be maintained securely when the slide fastener is closed.
Still further, according to the present invention, the distribution of the tightening forces on the connecting portion side and the coupling head side of the coupling element portions as described above may be exerted based on the yarn structures of the fixing warp yarns. Specifically, said at least one of the plurality of the element fixing warp yarns disposed on the side of said connecting portions has a larger fineness than any other one of the element fixing warp yarns disposed on the side of said coupling heads. The fineness is to be determined by a dimension and/or a weaving density, but should not be specified uniformly.
Even a monofilament could have a poor flexibility when it has a large fineness, if it is the same material. However, according to the present invention, when monofilaments are woven into a fastener tape in order to fix the coupling element portions which are composed of a monofilament, the respective adjacent fixing monofilaments intersect with each other between the respective adjacent coupling element portions. At this time, the larger the fineness of the monofilament is, the larger the intersecting angle at this time becomes. Therefore, the coupling element portions are restricted from moving in a parallel direction thereof. This can also be applied to a case where multifilaments or ordinary spun yarns are used for the fixing warp yarns to be disposed on the side of the coupling heads.
Still further, the characteristics of the fixing warp yarns disposed on the sides of the connecting portions and the coupling heads of the coupling element portions as described above can be specified in terms of their property. Specifically, according to the present invention, said at least one of the plurality of the element fixing warp yarns disposed on the side of said connecting portions has a lower pull elastic modulus than any other one of the element fixing warp yarns disposed on the side of said coupling heads.
This aspect of the present invention has developed the function in terms of the above-mentioned property by the difference of the pull elastic modulus. Specifically, the yarn with a high pull elastic modulus has a large elastic deformation, so that it can more easily deform by an external force than the yarn with a lower pull elastic modulus. Therefore, when the yarn that is composed of a thick monofilament and a low pull elastic modulus is used of the fixing warp yarns on the side of the connecting portions, the tightening force to the element row in the weaving process becomes larger than the other fixing warp yarns. Further, in a fastener tape as a product, the warp fixing warp yarns on the side of the connecting portions are unlikely to cause any deformation as compared to the other fixing warp yarns, even when an external force is applied. A value of the pull elastic modulus is not to be specified, because it should be relatively determined between the warp yarns on the connecting portion side and those on the coupling head side, depending on an intended use, application field of the fastener tape.
Still further, according to the present invention, the characteristics of the fixing warp yarns as described above is specified in terms of property, namely the rigidity of the fixing warp yarns. Specifically, said at least one of the plurality of the element fixing warp yarns disposed on the side of said connecting portions has a larger rigidity than any other one of the element fixing warp yarns disposed on the side of said coupling heads. The function is the same as described above. Similarly, a value of the rigidity is to be determined relatively determined between the warp yarns on the connecting portion side and those on the coupling head side, depending on an intended use, application field of the fastener tape.